This invention relates to a collapsible steering column assembly for a vehicle.
A vehicle steering column assembly is required to collapse in a controlled manner in the event of a vehicle crash. During a crash event, the steering column assembly should be able to accommodate collapse from the front of the vehicle, for example in order to accommodate intrusion of an engine compartment firewall and, in addition, the assembly should also be able to collapse away from the driver of the vehicle.
According to the present invention, there is provided a collapsible steering column assembly for a vehicle, the assembly including upper and lower subassemblies that are slidable one within the other, the upper subassembly being slidably mounted on a fixed mounting bracket mountable on a vehicle body part; and the lower subassembly including, at its end remote from said upper subassembly, an intrusion bracket that is slidably mounted on said mounting bracket, there being clamping means for applying clamping force between said mounting bracket and said intrusion bracket so as normally to inhibit relative sliding movement of the mounting and intrusion brackets but so as to allow such movement in the event of vehicle crash.
The intrusion bracket may also give support to a universal joint bearing assembly. This may be achieved through a pivot member pivotably mounted on the intrusion bracket.
The clamping means may include a clamping part extending through a guide slot in the mounting bracket and the clamping part may comprise at least one bolt connected to the intrusion bracket and tightened on either side of the guide slot. Two such bolts may be provided and the or each bolt may have a washer such as a plate washer to spread the tightening load on the edges of the guide slot. The or each washer may be coated with a low friction material to give a controlled breakaway load on the or each bolt, respectively. The guide slot may be recessed in a major surface of the mounting bracket and may extend parallel to the axis of the steering column. The slot may be a closed slot.
The pivot member may be connected to the intrusion bracket by means of pins that allow relative pivotal motion between the pivot member and the intrusion bracket. The intrusion bracket may be slidably mounted on the mounting bracket by means of complementary guideways.
The lower steering column subassembly may slide within the upper steering column subassembly and the two subassemblies may be interconnected through a profiled drive such as a spline interface.
An intermediate support bracket for the upper subassembly may be slidably mounted on the fixed mounting bracket in such a manner as to allow rake and/or reach adjustment of the steering column.